The fight lasts only for a few seconds and older students are then seen intervening, separating the boys and saying: ''Leave him.''
Rosehill College principal Sue Blakely told TVNZ the teachers had actually called for back-up on their walkie talkies and had been shouting to the boys to stop.
She told One News she had previously told staff members that their safety must come first and advised them not to intervene or put themselves at risk.
"If it had been males out there on duty they may well have restrained [the pupils], but that would have been their choice because they felt they were able to do so and preserve their own safety,'' she said.
"Nobody comes to work to end up being assaulted for whatever reason ... even if it's completely unintentional - it's traumatic.
"We have not had a staff member deliberately hit by a student, but we have had a couple of instances when a teacher has been glancingly hit or pushed while intervening."